OFFSET
0,6
LINKS
G. C. Greubel, Table of n, a(n) for n = 0..1000
D. Ford, J. McKay and S. P. Norton, More on replicable functions, Comm. Algebra 22, No. 13, 5175-5193 (1994).
FORMULA
Expansion of q^(1/2)*(eta(q)*eta(q^6)^4*eta(q^9)/(eta(q^2)*eta(q^3)* eta(q^18))^2) in powers of q. - G. C. Greubel, Jun 19 2018
a(n) ~ (-1)^n * exp(Pi*sqrt(2*n)/3) / (2^(5/4)*sqrt(3)*n^(3/4)). - Vaclav Kotesovec, Jun 29 2018
EXAMPLE
T36f = 1/q - q + q^3 + q^7 - 2*q^9 + 2*q^11 - 2*q^13 + 3*q^15 - 4*q^17 + ...
MATHEMATICA
eta[q_]:= q^(1/24)*QPochhammer[q]; a:= SeriesCoefficient[q^(1/2)*(eta[q] *eta[q^6]^4*eta[q^9]/(eta[q^2]*eta[q^3]*eta[q^18])^2), {q, 0, n}]; Table[a[[n]], {n, 0, 50}] (* G. C. Greubel, Jun 19 2018 *)
PROG
(PARI) q='q+O('q^50); Vec((eta(q)*eta(q^6)^4*eta(q^9)/(eta(q^2)*eta(q^3)* eta(q^18))^2)) \\ G. C. Greubel, Jun 19 2018
CROSSREFS
KEYWORD
sign
AUTHOR
Michael Somos, Aug 28 2005
STATUS
approved